I'm sure the Republicans will keep trying to skew elections as long as possible, but I'm not convinced it'll work in their favor for as long as they think it will or as democracy-loving people fear. The key is demographic shift, and it's not just limited to existing liberal strongholds.
Non-white voters are representing an increasingly large section of the population in many areas, and younger voters are much more likely to vote Democrat. While it's far from guaranteed, there is a real possibility that the Republicans are backing themselves into a corner where no amount of voter suppression (short of outright falsifying numbers) gets them enough votes to win the presidency. There are only so many old, bigoted white men to go around.